(So i'm just gonna copypasta my post from intros lol)
I just bought my first bike on craigslist and fell in love. I just can't stand that I don't know very much about it(or bikes in general). I try to do research on it but come up empty handed. I'm happy to be on the bike forums and I can't wait to learn about bikes and cycling.
This is it. I took it to a local shop to get the wheels trued(a car came up behind me really fast and scared me. i swerved and hit another car lol.) and he told me a little about how Schwinn World bikes were from like the early 80s but didn't go into detail about the bike itself. The bike isn't in the best of shape. The chain is rusted, the seat and the bar grips are all boffed up, and now the back tire is popped, i don't think the tubes have ever been changed. The person who sold it to me said someone bought it for their kid, they used it maybe twice and then put it away. It's been in a shed for a very long time. If you have any info on this bike or how to fix it up i'd really appreciate it.

Congrats on a nice bike! Looks like a 1987 World, if I'm not mistaken. Take a gander at the catalog:

It doesn't sound like the bike has any big problems to worry about. Going from the top:

1. Replace the chain. I like KMC chains. Chains rated for 5 or 6 speeds will work best.
2. Replace the grips. Those foam grips were never nice to begin with. Get some cloth tape, get your bike shop to install it while you watch and learn. Tressostar/Velox and Newbaum's are good makes.
3. The saddle looks functional. I wouldn't worry about it, you can always get a cheap racing type saddle later on.
4. Tubes are easy to get and generally fit a number of rim sizes. You need tubes for 27x1/4", or "32-630". Sometimes the box will state a range, like "28/32-630". As long as your size is within that range you'll be fine.
5. Examine the tires. Are they rotten/cracked/perforated in any way? Then look for replacements. Sad truth: Rubber doesn't last forever.